KR20080068712A - High-barrier packaging material - Google Patents

Abstract

The invention involves a high-barrier packaging material comprising at least one outer layer of kraft paper, at least one center layer of high-barrier metallized polyethylene terephthalate, and an inner layer of linear low density polyethylene. The packaging material has excellent water vapor and oxygen barrier properties.

Description

High-Barrier Packaging Material {High-Barrier Packaging Material}

The present invention relates to high-barrier packaging materials.

In particular packaging of certain products, such as foodstuffs, it is highly desirable to prevent or prevent permeation of oxygen and / or water vapor through the packaging. Permeation of oxygen or water vapor is not necessarily detrimental to the product itself, but exposure to these elements can degrade the quality and shelf life of the product.

To prevent degradation of such products, plastic films are often used for packaging. One such plastic film is polyethylene terephthalate (PET), which is a polyester of terephthalic acid and ethylene glycol. PET can be obtained through condensation of dimethyl terephthalate with ethylene glycol or through condensation of terephthalic acid with ethylene glycol or ethylene oxide. The excellent thermal properties of PET allow for processing and use over a wider temperature range (-70 ° C. to 150 ° C.) than many conventional packaging films.

In many cases, PET is metallized to improve its barrier properties. Metallization is the process of applying a metallic coating on another surface. PET can be metalized through a variety of processes including vacuum metallization, physical evaporation, sputtering, indirect metallization, plating or painting. Most commonly, PET is vacuum-metalized with a layer of aluminum. In this process, aluminum can be heated, melted and evaporated in a chamber under high vacuum. The vaporized vapor then moves through the chamber and condenses on a lower temperature surface such as PET.

Metallized PET is often preferred over other metallized plastics because it has low permeability to oxygen, other gases, and water vapor. A single web of metallized PET is about 0.5 to 0.8 cm ³ / m ^2/24 sigan oxygen barrier between (23 ℃, 0% relative humidity (RH)) and from about 1 g / m ^2/24 sigan (38 ℃ , At 90% RH). Metallized PET also exhibits good bending crack resistance, tear resistance and chemical resistance. Metallized PET is a common choice in plastic packaging, but it has several disadvantages. For example, surface defects such as scratches or marks may appear on the metal surface of the metallized PET. Such surface defects are often the main route of gas and moisture permeation.

In response to this surface defect, a high-barrier metallization process has emerged. For example, British Patent No. 2,103,999 (Bodin et al.) Relates to a method of bonding two layers of metallized PET to improve both oxygen and water vapor barriers. In one embodiment of the invention, Bodine describes bonding two metalized PET layers to a metal surface versus a metal surface. By laminating the two metalized surfaces together, the appearance of surface defects is significantly reduced. The performance of such laminate structures is significantly improved over single layer metallized structures. For example, the high-barrier water vapor barrier of the metallized PET laminate may be between about 0.1 to 0.13 g / m ^2/24 hours, the oxygen barrier may be about 0.6 cm ³ / m ^2/24 hours.

Similarly, European Patent No. 0,154,248 to Kelly relates to film laminates having an oxygen and / or water vapor barrier. The laminate includes two layers of metallized thermoplastic films, joined by a layer of adhesive to a metal surface to metal surface. The two layers of film may comprise one layer of polyolefin and one layer of polyolefin, regenerated cellulose or polyamide. In one embodiment, the polyolefin layer can be LLDPE. The barrier properties of the laminates are said to be substantially better than the sum of the barrier properties of the constituting metallized films.

U. S. Patent No. 5,888, 648 (Donovan et al.) Relates to a multilayer film utilizing an outer main film substrate layer, an intermediate layer and an inner sealing layer. The main film substrate may be a high-barrier metallized PET, the middle layer may be LLDPE, and the sealing layer is an ethylene-propylene random copolymer, an ethylene-propylene-butene random terpolymer, or a metallocene plastic It may be a stormer. The document clearly claims the provision of both said intermediate and sealing layers.

Despite the presence of high-barrier films, the prior art does not provide high-barrier packaging materials with good oxygen and moisture barriers, good bend-cracking, tearing, puncture and chemical resistance, good sealing properties and high elongation. Therefore, it would be useful to provide packaging materials useful for meeting these needs.

Summary of the Invention

Therefore, in short, the present invention relates to a novel high-barrier packaging material for packaging a product. The packaging material comprises at least one outer layer of kraft paper, the outer layer being bonded to at least one central layer of high-barrier metallized PET, the central layer being made of linear low density polyethylene (LLDPE) To at least one inner layer. In the present invention, the inner layer is in direct contact with the product.

Among the several advantages shown to be achieved by the present invention, it has a good oxygen and moisture barrier, good bend-cracking, tearing, puncture and chemical resistance, good sealing properties and high elongation. The packaging material of the invention is also economically produced.

1 is an enlarged cross-sectional view of a high-barrier packaging material of the present invention.

2 is an enlarged cross-sectional view of the high-barrier pavement material of the present invention, wherein the pavement material has two central layers of high-barrier metallized PET.

Referring now to embodiments of the present invention in detail, one or more embodiments thereof are described below. Each embodiment is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For example, features shown and described as part of one embodiment can be used in another embodiment to create another embodiment.

In other words, the present invention is intended to cover such modifications and variations as fall within the scope of the appended claims and their equivalents. Other objects, features and aspects of the present invention will be described in the following detailed description and will be apparent therefrom. It is to be understood by those skilled in the art that the description is merely illustrative of exemplary embodiments and is not intended to limit the broader aspects of the invention.

According to the present invention, new high-barrier packaging materials for packaging products have been found. The packaging material comprises at least one outer layer of kraft paper, the outer layer being bonded to at least one central layer of high-barrier metallized PET, the central layer being made of linear low density polyethylene (LLDPE) To at least one inner layer. In the present invention, the inner layer is in direct contact with the product.

In the present application, the term "high-barrier" means any material that can prevent the entry of other materials, such as gases, flavors, vapors or aromas. As it used here the term "high barrier" can mean any material having an oxygen transmission rate and about 0.3 g / m and water vapor permeability of less than ^2/24 hours of less than about 0.6 cm ³ / m ^2/24 hours .

As used herein, the term "outer layer" means a layer located outside of the packaging material. The outer layer may comprise several plies, but for the purposes of the present invention, the plies comprise the same material. The term "central layer" means a layer located in the middle of the outer and inner layers. The central layer may comprise several layers, but for the purposes of the present invention the layers comprise the same material. The term "inner layer" means a layer located inside the packaging material. The inner layer may comprise several plies, but for the purposes of the present invention the plies comprise the same material.

When the packaging material of the invention is formed in the form of a bag designed to contain a product, the inner layer is a layer in direct contact with the product. The term "product" as used herein may include any product that will be affected by moisture or gas permeation. For example, a "product" may include liquid, solid or powdered foodstuffs or beverages, pharmaceuticals or nutritional supplements. In certain embodiments, the "product" may comprise a powdered dairy formulation. In other particular embodiments, the “product” may comprise a child or infant preparation.

The combination of high-barrier metallized PET and LLDPE in the present invention provides many advantages over conventional packaging materials. Metallized PET is known to improve bending crack resistance, tear resistance and chemical resistance compared to foil-based structures. LLDPE has good sealing properties, good puncture resistance, good optical and mechanical properties, high elongation, good impact strength and is very economical. That is, the laminate of the present invention provides a packaging material that combines these advantages.

In addition, the packaging material of the present invention has an excellent oxygen and vapor barrier. Oxygen barrier provided by the present invention is between about 0.3 to 0.6 cm ³ / m ^2/24 sigan (23 ℃, 0 at% RH). Water vapor barrier provided is between about 0.1 to 0.3 g / m ^2/24 sigan (38 ℃, at 90% RH). These barrier features are better than those indicated by some of the prior art discussed above.

The present invention uses at least one outer layer of kraft paper. In one embodiment, the packaging material comprises two outer layers of kraft paper. In another embodiment, the present invention comprises three outer layers of kraft paper. In these embodiments, the kraft paper layers can be adhered to each other using polyvinyl acetate.

Kraft paper is mainly made from wood pulp produced by a modified sulfate pulping process. This is a relatively coarse paper that is partly noted for its strength. It may be striped, calendared, with a transparent fringe, and has an acceptable surface for printing. Its natural unbleached color is brown, but using semi-bleached or fully bleached sulphate pulp it can be produced in lighter shades of brown, cream shade and white.

In the present invention kraft paper is bonded to a high-barrier metallized PET layer. In one embodiment, the kraft paper can be adhered to the high-barrier metallized PET layer using, for example, a hot melt adhesive glue spot. Any adhesive known in the art may be used in this embodiment, and other adhesive means may be used. In one embodiment, the adhesive can be an acrylic copolymer Durabond PC8100CM. The pressure sensitive adhesives are available from Revertex Finewaters Sdn Bhd.

The packaging material of the present invention comprises at least one central layer of high-barrier metallized PET. The high-barrier metallized PET central layer comprises two layers of metallized PET, glued together based on metal surface to metal surface. The adhesion based on the metal surface to the metal surface protects the metallized surface from scratches or marks, preventing surface defects that may affect the barrier properties of the film. The adhesive between the two metal layers of high-barrier metallized PET can be any known in the art. In one embodiment, one-component or two-component adhesives can be used with or without solvent. In a particular embodiment, the adhesive between the two metal layers can be polyurethane.

The metal layer of the high-barrier metallized PET can be deposited on the PET by any means known in the art. For example, the metal layer may be deposited on the PET layer by vacuum metallization, physical evaporation, sputtering, indirect metallization, plating or painting. In one embodiment, the metal layer is deposited on the PET layer by vacuum metallization.

The metal layer of the metallized PET may comprise various metals such as aluminum, silver, chromium or a combination thereof. In one particular embodiment, the metal layer of the present invention comprises aluminum.

In one embodiment, the packaging material comprises two central layers of high-barrier metallized PET. Using two central layers of high-barrier metallized PET provides a more effective oxygen and water vapor barrier. The two central layers of high-barrier metallized PET can be glued together using any adhesive known in the art to be effective for bonding the PET layer. In certain embodiments, the two central layers are bonded using a urethane adhesive.

The present invention also uses an inner layer of LLDPE. LLDPE is a copolymer of ethylene with one or more comonomers selected from C ₄ to C ₁₀ alphaolefins. The molecules of the copolymer include long chains with few branched or crosslinked structures. The molecular structure contrasts with conventional low or medium density polyethylenes that are more highly branched than their respective counterparts. LLDPE typically has a density ranging from about 0.916 g / cm ³ to about 0.925 g / cm ³ . The LLDPE inner layer can be adhered to the high-barrier metallized PET layer using a dry adhesive. In a particular embodiment, the dry adhesive comprises a two component polyurethane adhesive.

In certain embodiments, the LLDPE inner layer may be replaced with any polyethylene-based material or any plastic having sealing properties.

The dimensions of the packaging material of the invention can vary within very wide limits. The packaging material should be thin enough to be used for packaging but thick enough to have sufficient mechanical resistance to handle. In one embodiment, the thickness of the PET layer is between about 4 μ and 300 μ. In yet another embodiment, the thickness of the PET layer is between about 10 μ and 200 μ. The thickness of the aluminum layer may be between about 0.02 μ and about 0.06 μ. In yet another embodiment, the thickness of the aluminum layer can be between about 0.03 μ and 0.04 μ. The adhesive layer between the two metal layers may have a thickness of about 1 μ to about 10 μ. In yet other embodiments, the thickness of the adhesive can be between about 2 μ and 4 μ. That is, the total thickness of the high-barrier metallized PET layer of the present invention may be between about 8 μm and 600 μm. In a particular embodiment, the high-barrier metallized PET layer may be between about 10 μ and 100 μ. In another embodiment of the invention, the thickness of the high-barrier metallized PET layer may be about 12 μ.

The PET layers of the high-barrier metallized PET need not have the same thickness. Likewise, metal layers of high-barrier metallized PET need not be the same metal or have the same thickness.

The thickness of the LLDPE layer of the present invention may be between about 20 μ and 200 μ. In one embodiment, the LLDPE layer of the present invention may be between about 30 μ and 100 μ. In a particular embodiment of the invention, the LLDPE layer may be between about 50 μ and 70 μ.

The ply of kraft paper used in the present invention may have a thickness between about 20 g / m ² and 100 g / m ² . In another embodiment, the ply of the kraft paper of the present invention is between about 50 g / m ² and 100 g / m ² . In another embodiment, the ply of kraft paper used in the present invention is about 75 g / m ² .

The packaging material of the present invention can be used to package any product known in the art that requires a high moisture and / or oxygen barrier. In one embodiment, the material is used to package food, pharmaceuticals, industrial products or agricultural products. Solid, powdered or liquid products may be packaged by the present invention.

Referring now to the drawings, FIG. 1 shows a cross-sectional view of the high-barrier packaging material 10 of the present invention. In this embodiment of the invention, the packaging material has three plies 20, 21 and 22 of kraft paper as the outer layer of material. In this embodiment, the present invention has a single central layer 30 of high-barrier metallized PET. The central layer 30 of high-barrier metallized PET comprises two layers 31 and 35 of metallized PET, wherein the metal surfaces are glued together into a layer 34 of polyurethane have. Each layer 31 and 35 of metallized PET has layers 32 and 37 of PET and layers 33 and 36 of aluminum. The inner layer 50 of the packaging material 10 comprises LLDPE.

2 shows a cross-sectional view of the high-barrier pavement material 100 of the present invention having two central layers 130 and 140 made of high-barrier metallized PET. The high-barrier metallized PET layer 130 includes two layers 131 and 135 of metallized PET, bonded to a layer 134 of polyurethane. Similarly, high-barrier metallized PET layer 140 includes two layers 141 and 145 of metallized PET, bonded to a layer 144 of polyurethane.

In FIG. 2, each metallized PET layer consists of a layer of PET and a layer of aluminum. For example, the metallized PET layer 131 includes a layer 132 of PET and a layer 133 of aluminum. Metallized PET layer 135 includes a layer 137 of PET and a layer 136 of aluminum. Metallized PET layer 141 includes a layer 142 of PET and a layer 143 of aluminum. Metallized PET layer 145 includes a layer 147 of PET and a layer 146 of aluminum. The inner layer 150 of the packaging material 100 is LLDPE. The outer layers 120, 121 and 122 of the material are three plies of kraft paper.

The following examples describe various embodiments of the present invention. Other embodiments within the scope of the claims set forth herein will be apparent to those skilled in the art upon consideration of the detailed description or practice of the invention as disclosed herein. In addition to the examples, the specification is also to be regarded as illustrative only, the scope and spirit of the invention being indicated by the claims that follow the examples. In the examples, all percentages are given on a weight basis unless otherwise indicated.

Example  One

This example illustrates the manufacture of the high-barrier packaging material of the present invention. This example also illustrates the properties of the high-barrier packaging material under test conditions.

A 12 μ layer of high-barrier vacuum-metalized PET was bonded to a 70 μ layer of LLDPE using a two-component polyurethane adhesive. Thereafter, three layers of natural kraft paper (75 g / m ² ) were adhered to opposite sides of the high-barrier vacuum-metalized PET using a hot melt adhesive glue spot of Durabond PC8100CM. The packaging material was formed. The packaging material was then formed in the form of a bag, filled with milk powder and sealed. The bag was 865 mm long, 539 mm wide and 164 mm bottom wide.

The oxygen barrier bag was measured to be about 0.6 cm ³ / m ^2/24 sigan (23 ℃, at 0% RH). The water vapor barrier bag was measured to be about 0.3 g / m ^2/24 sigan (38 ℃, at 90% RH).

The bag was subjected to a drop test using a drop tester and Drop Tester Model # OSK-02 to confirm the stability and toughness of the bag. The bag was filled with a load of 25 kg and dropped in both vertical and horizontal directions at a height of 1.0 to 1.5 m. The bag was dropped 10 times vertically and 10 times horizontally. The result was satisfactory and no rupture was observed.

The bag was subjected to tensile strength tests on kraft paper and high-barrier vacuum-metalized PET. Tensile strength tests were performed using a logger, Shimadazu logger or tensile tester, Model # AGS 100C. Kraft paper was tested vertically and horizontally at 10 mm / min using a gauge length of 100 mm and a sample width of 15 mm. The high-barrier vacuum-metalized PET was tested vertically and horizontally at 300 mm / min, using a gauge length of 100 mm and a sample width of 15 mm. The tensile strength of the kraft paper was determined to be 10.92 kg in the vertical direction and 5.39 kg in the horizontal direction. The tensile strength of the high-barrier vacuum-metalized PET was determined to be 4.47 kg in the vertical direction and 5.03 kg in the horizontal direction. The results were acceptable.

The bags were also tested for closure, slip-proof and appearance quality. The suture test was performed using a Shimadatsu automatic recording or tensile tester, Model # AGS 100C, and an over-tapping machine. The test determines the actual material strength after the sealing process. The material was determined to have a tube strength of 4.54 kg and an over-tapping strength of 2.39 kg.

An anti-slip test was performed using a slip tester, Yasuda Seiki Slip Tester Model # 162. The test measures the anti-slip angle during transport. The material was measured to have a slip-resistant value of 37 ° in both vertical and horizontal directions.

The appearance of the bag was visually observed, which was satisfactory in terms of printability as well as position, condition and surface. Printing designs, colors and features were all observed to be satisfactory.

Example  2

This example illustrates another high-barrier pavement material of the present invention.

Two 12 μ high-barrier metallized PET layers were adhered to each other using urethane. In addition, one high-barrier metallized PET layer was attached to a 50 μ layer of LLDPE using a two-component polyurethane adhesive. Next, three plies of natural kraft paper (75 g / m ² ) were adhered to opposite high-barrier vacuum-metalized PET layers using hot melt adhesive glue spots of Durabond PC8100CM. This formed the packaging material of the present invention. The packaging material was then formed in the form of a bag, filled with milk powder and sealed. The bag was 866 mm long, 540 mm wide and 164 mm wide at the bottom.

The oxygen barrier bag was measured to be about 0.3 cm ³ / m ^2/24 sigan (23 ℃, at 0% RH). The water vapor barrier bag was measured to be about 0.1 g / m ^2/24 sigan (38 ℃, at 90% RH).

The bag was subjected to a drop test using a drop tester and a drop tester OSK-02 to confirm the stability and toughness of the bag. The bag was filled with a load of 25 kg and dropped in both vertical and horizontal directions at a height of 1.0 to 1.5 m. The bag was dropped 10 times vertically and 10 times horizontally. The result was satisfactory and no rupture was observed.

The bag was subjected to tensile strength tests on kraft paper and high-barrier vacuum-metalized PET. Tensile strength tests were performed using an auto recorder, Shimadatsu auto record or tensile tester, Model # AGS 100C. Kraft paper was tested vertically and horizontally at 10 mm / min using a gauge length of 100 mm and a sample width of 15 mm. The high-barrier vacuum-metalized PET was tested vertically and horizontally at 300 mm / min, using a gauge length of 100 mm and a sample width of 15 mm. The tensile strength of the kraft paper was determined to be 10.08 kg in the vertical direction and 4.85 kg in the horizontal direction. The tensile strength of the high-barrier vacuum-metalized PET was determined to be 7.68 kg in the vertical direction and 8.92 kg in the horizontal direction. The results were acceptable.

The bags were also tested for closure, slip-proof and appearance quality. The suture test was performed using a Shimadatsu automatic recording or tensile tester, Model # AGS 100C, and an over-tapping machine. The test determines the actual material strength after the sealing process. The material was determined to have a tube strength of 6.52 kg and an over-tapping strength of 4.90 kg.

An anti-slip test was performed using a slip tester, Yasuda Seiki Slip Tester Model # 162. The test measures the anti-slip angle during transport. The material was determined to have a slip-proof value of 34 to 35 ° in both vertical and horizontal directions.

The appearance of the bag was visually observed, which was satisfactory in terms of printability as well as position, condition and surface. Printing designs, colors and features were all observed to be satisfactory.

All references cited herein, including, without limitation, all articles, publications, patents, patent applications, publications, texts, reports, manuscripts, booklets, books, internet submissions, journal articles, periodicals, etc., are hereby incorporated in their entirety. It is hereby incorporated by reference. The discussion of the references herein is merely to summarize what is claimed by the authors and does not endorse that any references constitute prior art. Applicants reserve the right to challenge the accuracy and validity of cited references.

While preferred embodiments of the invention have been described using specific terms, apparatus, and methods, such descriptions are for illustrative purposes only. The words used are words of description rather than limitation. It is to be understood that changes and variations may be made by those skilled in the art without departing from the spirit and scope of the invention as set forth in the claims below. In addition, it should be understood that aspects of the various embodiments, in whole or in part, may be interchanged. For example, methods of making commercially available sterile liquid nutritional supplements prepared according to these methods are illustrated, but other uses are contemplated. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred embodiments contained therein.

Claims (19)

a) at least one outer layer of kraft paper, b) the outer layer is bonded to at least one central layer of high-barrier metallized polyethylene terephthalate, c) said central layer is bonded to at least one inner layer of linear low density polyethylene, said inner layer being in direct contact with the product, High-barrier packaging material for packaging products. The packaging material of claim 1, wherein the central layer of high-barrier metallized polyethylene comprises two layers of metallized polyethylene terephthalate bonded together on a metal surface to metal surface basis. 3. The packaging material of claim 2 wherein the metal surfaces are bonded together using a polyurethane adhesive. The packaging material of claim 1 comprising two outer layers of kraft paper. The packaging material of claim 1 comprising three outer layers of kraft paper. The packaging material of claim 1 comprising two central layers of high-barrier metallized polyethylene terephthalate. The packaging material of claim 1, wherein the high-barrier metallized polyethylene terephthalate is metallized through vacuum metallization. The packaging material of claim 1, wherein the metal layer of the high-barrier metallized polyethylene terephthalate comprises aluminum. The packaging material according to claim 1, which is used for packaging foodstuffs, pharmaceuticals, industrial products or agricultural products. The packaging material of claim 1, wherein the packaging material is formed in the form of a bag. The packaging material of claim 1, wherein the high-barrier metallized PET layer has a thickness between about 8 microns and 600 microns. The packaging material of claim 1, wherein the high-barrier metallized PET layer has a thickness between about 10 μm and 100 μm. The packaging material of claim 1, wherein the high-barrier metallized PET layer has a thickness of about 12 μ. The packaging material of claim 1, wherein the LLDPE layer has a thickness between about 20 microns and 200 microns. The packaging material of claim 1, wherein the LLDPE layer has a thickness between about 30 μm and 100 μm. The packaging material of claim 1, wherein the LLDPE layer has a thickness between about 50 microns and 70 microns. The packaging material of claim 1, wherein the weight of the kraft paper is between about 20 g / m ² and 100 g / m ² . The packaging material of claim 1, wherein the weight of the kraft paper is about 75 g / m ² . A packaging material substantially the same as shown and described herein.

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